Subwoofer Pro Eminence Omega 18 (EPS18-600)???

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Hi
The my main idea was to make subwoofer like JBL Synthesis subwoofer with driver-JBL Pro 2242H, not going to very low Hz, but with high db
So I need big 18” Pro Sub driver.
Just bought on E-bay Eminence Omega 18 EPS18-600
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7625870602&rd=1&sspagename=STRK:MEWN:IT&rd=1

(fs) 28Hz
(Re) 5.1 Ohm
(Qes) 0,25
(Qms) 5,53
(Qts) 0,24
(Vas) 354 liter
(Xmax) 4.8mm
(Xmech) 32.00mm
(BL) 25 T-M

1.
Put the one in to BassBox6
The results are bad Vb=135l, Fb=32Hz, F3=585Hz, (vented box)
why F3=585Hz? amplitude response curve are started to slow down from 585 Hz.
I figured out that if I change in driver parameter BL to 12Tm or just delete, then amplitude response curve started to be OK and slow down from 61Hz F3=61Hz.

What is parameters BL? Why this so much depend on F3 and on Bass response?
Can I make good subwoofer on this driver?

2.
In BassBox6 Box properties I can chouse
High fidelity – less box, higher F3. volume = 65 l, F3= 61Hz Fb=42Hz
Extended Bass – higher volume box, lower F3. volume = 136 l, F3= 68Hz Fb=32Hz
What to chouse to make good quality subwoofer. Remember I want to make like JBL Synthesis Subwoofer not going to very low but with high db.


3.
Side firing or bottom firing?
JBL make Side firing but most other bottom firing.


Subwoofer Eton 12-680/62HEX your suggestion?

Hi
I need to make subwoofer for Home Theater so vented box to make high SPL
On Eton 12-680/62HEX
Fs=26Hz, Vas=150l, Qts=0.34
BassBox6 gave me Vb=69l, Fb=29Hz, F3=38Hz. I guess this is OK
But your advise will be welcome.

Side firing or bottom firing to make what is difference?
If bottom firing how high should be driver from bottom?
 
I'd try a bigger box, like 250 to 300 liters (8 to 10 cubic). I'm pretty sure that's what I used when I built a couple of subs using a very similar Eminence driver. I don't know how flat it was, but it could make the floor shudder and clothes vibrate when playing drum'n'bass.

About floor firing; I'd be afraid of the cone sagging.

I don't think it's ideal for a horn, but it is mentioned as an option for the 186 horn cabinet at http://www.speakerplans.com

I'm seriously thinking of building up a couple of those, seeing as I have two of those Eminence drivers sitting in cabinets I don't use.
 
The results are bad Vb=135l, Fb=32Hz, F3=585Hz, (vented box)
Perhaps an error or something? In WinISD Pro I get the F3 at 62 Hz. So very similair to your sim with BL deleted.

The BL does tell you something about the strength of the motor, a high BL will generally combine with a low Qts, making the speaker efficient but less suited for subwoofer use. Lower BL the other way 'round
Luckily the Omega has an fairly low Fs so it can be used for some subwoofer action anyway.

Those 135 ltr tuned to 32 Hz sounds about right. You can even tune lower, with bigger volume because the roomgain will compensate for a certain amount of roll off (using it inroom right?)

I would make it down firing as the resulting lack of distortion will make it nearly impossible to locate the sub. The volume in front of the driver can act as an low pass filter as well (still need crossover tho).
Cone sagging is ussually not a problem with PA drivers because of the (relatively) stiff suspension/spider(s).

Stand for downfiring. Downfiring 18" sub

With kind regards Johan
 
Not optimized for sub use

You'd need significant eq to get the driver to be flat down low. Fortunately, the driver has the surface area and power handling to live with EQ and still give you high SPL at low frequencies (or high by my standards, not a "basshead"). I'd go with a massive (Qtc .5) box and a first order boost slope.
 
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